Date: Tue, 20 Feb 1996 12:44:00 +0200
From: "Costas A. THANOS" (cthanos@atlas.uoa.gr)
Subject: cryodormancy
Hi everyone,
LOW TEMPERATURE IMPOSAL OF DORMANCY
Recently, while working on the ecophysiology of seed germination in a number of
Mediterranean geophytes we have encountered several cases of cryodormancy.
More specifically, seeds can germinate optimally (in darkness) over a range, say 10-
20 C, but not at 5 C. When seeds that have imbibed at 5 C are eventually
transferred to the optimal temperature, say 15 C (always in darkness), they cannot
germinate (while still viable). This is what we term cryodormancy and please note
that seeds imbibing in supraoptimal temperatures, say 25 C, cannot germinate as
well, but no secondary dormancy is being imposed (that is they can germinate upon
transfer to the optimal temperature).
Now, apart from the indirect evidence of a secondary dormancy imposal by low
temperatures in:
a. Rumex crispus & R. obtusifolius (Totterdell & Roberts 1979)
b. Arabidopsis thaliana (Baskin & Baskin 1983), and
c. Ranunculus sceleratus (Probert et al 1989),
is anyone aware of a straightforward example of dormancy induction by low
temperatures (in the way described above)?
Any help, suggestion or comments are mostly welcome. To follow Marc's example,
either beer or ouzo may be offered!
Thanks
Costas A. Thanos (Athens, Greece)
cthanos@atlas.uoa.gr
--------------------------------------
Date: Mon, 26 Feb 1996 13:12:32 +0000 (GMT)
Sender: Robin Probert (rp03wk@lion.rbgkew.org.uk)
Subject: cryodormancy
Costas
There are a number of examples in the literature of low temperature
induction of dormancy in winter annuals (reviewed in: Probert R J 1992,
The role of temperature in germination ecophysiology. In: Seeds: The
Ecology of Regeneration in Plant Communities. M Fenner ed. CAB
International) but I'm not sure that these will provide the
'straightforward' examples you seek.
I suggest you also look at Harro Bouwmeester's PhD for detailed studies
on the effects of temperature (climatic) on seasonal dormancy patterns:
Bouwmeester H J 1990, The effect of environmental conditions on the
seasonal dormancy pattern and germination of weed seeds. PhD Thesis.
Agriculture University, Wageningen, The Netherlands.
If this information qualifies for the prize, I'll take the beer !
Robin Probert
Seed Conservation Section
Royal Botanic Gardens, Kew
Wakehurst Place
RH17 6TN, UK
-------------------------------------------------
Date: Tue, 27 Feb 1996 07:25:35 -0600
From: jdekker@iastate.edu (Jack Dekker)
Subject: "cryodormancy"
Costas,
Consider also: Baskin and Baskin. 1985. The annual dormancy cycle
in buried weed seeds: a continuum. BioScience 35:492-498. We are observing
similar patterns in Setaria, a summer annual, here in our midwestern US
agricultural seed banks in both seed, caryopsis and embryos of that weedy
group.
Make mine an ouzo.
Jack Dekker
Jack Dekker, 3214 Agronomy Hall
Iowa State University, Ames, Iowa 50011
TEL: (515)294-8229; FAX: (515)294-3163
E-Mail: (jdekker@iastate.edu)